Common electric wall units consist of a socket having two or three holes in which the prongs of a plug are inserted. The structure of this socket-plug configuration poses a safety threat to children or others who may get burned or shocked upon sticking a metal object or fingers in the socket. This is a particular danger to blind people who must deal with their fingers to find the holes in a socket.
Another problem is that plugs are often difficult to remove from a socket because of a tight fit. Often the person having difficulty will twist the plug to loosen it or will pull on the wire to gain leverage. In both cases, damage to the plug by exposing a wire may result.